Introduction
In this article we will consider Central Auditory Processing Disorder (CAPD) and its overlap with ADHD. Teaching and parenting considerations for the student with CAPD features will be reviewed.
A neuropsychologist is interested in brain-based problems with memory, academic achievement, attention, and other cognitive functions. While there are many descriptive terms used by parents and teachers and clinicians, and while these may be useful, the neuropsychologist is most interested in the ways in which these descriptors "map onto" known brain-behavior relationships.
For example, the word dyslexia comes from the Greek dys (trouble with, or limitations with) and lex (word). So, we have a sophisticated word for what we may already have known - we have a student who has trouble with words. In the strictest use of the term dyslexia we would be referring to a student who has a brain-based difficulty with reading. These include difficulty with understanding grapheme-phoneme relationships for example, or challenges with relating that which the eyes see to the sounds that make up the spoken language. A student with reading problems for other, not brain-based, reasons would not be considered dyslexic in this strict sense. If he or she primarily spoke another language at home, for example, or if other problems (ADHD or mental health issues or chaotic school or home environment) prevented age-appropriate reading mastery, we would not likely think of the student as "dyslexic."
Now in the case of CAPD, are we dealing with a brain-based problem? If so, is it distinguishable from other, related disorders? And if not, then what do we make of our students and children who present with what certainly appear to be frank limitations
processing that which their ears are hearing? Is CAPD just a descriptive label?
CAPD: An Overview
First let's take a look at the term itself: Central Auditory Processing Disorder.
Fortunately, this is term in plain English. The "central" in CAPD refers to a cognitive processing disorder which is not related to "peripheral" auditory problems. That is, the
student can "hear" just fine, but is not able to derive meaning from auditory language at a level which would be predicted based on age or education or intellectual ability.
The words "auditory processing" in CAPD suggest that the disorder is specific to this domain of cognitive functioning, and not part of a broader limitation such as a general intellectual limitation.
And herein lies the rub, for the purposes of a column about ADHD. There is a lively controversy among clinicians and academics about whether CAPD, as currently conceptualized, can be reliably distinguished from other disorders such as learning disorders and/or ADHD. In light of what we already know about ADHD, let's look at some of the symptoms associated with CAPD:
- easily distracted by loud or sudden noises
- behavior and performance are improved in quieter settings
- difficulty following directions
- reading, spelling, writing difficulties
- difficulty understanding abstract information
- disorganized or forgetful
- difficulty following conversations
- frequently says "huh" or "what"
- poor auditory attention
- extreme distractibility
- Difficulty listening when there is background noise
- Limitations with auditory memory span
The overlap between these symptoms and ADHD is apparent, and some neuropsychologists have wondered whether in fact CAPD might be a descriptive (rather than diagnostic) term for a subset of the challenges experienced by students with ADHD.
A "Discipline Bias"?
In his influential 600-page text on the topic of ADHD, Dr. Russell Barkley dedicates a scant two paragraphs to the issue of CAPD. (Readers: I haven't taken a look at Dr. Barkley's 2005 revision of ADHD: A handbook for diagnosis and treatment . If you have, I'd be interested to know whether the issue of CAPD is addressed differently in this new edition.) This likely points to something of a "discipline bias" at play here. While psychologists and neuropsychologists will make infrequent use of the term, speech and language professionals are much more likely to speak of CAPD or APD as it is sometimes called.
This discipline bias is not uncommon; the issue of sensory integration disorder , for example, is another which is addressed differently among clinicians of different disciplines and backgrounds. However, it can be confusing for parents to hear different clinicians using different language to describe a student, or to have a treating doctor dismiss a diagnostic term which another clinician has presented as quite "real."
To be frank, science is at a certain point in the clarification of these issues which might be described as, well.."not there yet." The challenges mentioned above are just a few of those which clinicians and academics, as well as teachers and parents, are considering as they evaluate and teach and rehabilitate students with language-specific limitations. In a 2005 article, Stuart Rosen ( University College , London ) references a Winston Churchill quotation in describing CAPD as "a riddle wrapped in a mystery inside an enigma." He is commenting here on the ongoing challenge of determining whether CAPD can be distinguished not only from peripheral hearing loss, but also from supramodal factors. I try to avoid unnecessary jargon but this term supramodal will likely be useful for our understanding of CAPD/ADHD relationships and, moreover, will pop up again and again in scientific and clinical articles.
Upstream and Downstream
I like to use the terms "upstream" and "downstream" when I think of cognitive functions. The downstream functions are the more basic or elementary functions, while upstream functions are the higher or more sophisticated functions. Downstream functions are necessary for those functions which are upstream. For example, perhaps the most basic downstream function is arousal. Unless a student is sufficiently aroused (awake and capable of receiving sensory information), it makes no sense to ask questions of higher-level "upstream" functions such as problem solving or memory.
In the case of auditory processing, a basic or "downstream" function is simple auditory processing - the capacity to hear a string of sounds and get meaning out of that string. A teacher says "open your math books" and, by some miracle of human intelligence, most students indeed open up the appropriate text. They've made sense of the incoming auditory stimuli and have understood those stimuli as a request.
"Upstream" from that basic function is the capacity to pay attention over a period of time, inhibit distractibility, and guide behavior by such internalized rules as "make eye contact with the teacher" or "raise my hand before getting out of my seat." Those functions and behaviors are noted to be limited among students with ADHD, and so for the purpose of our discussion here we see that ADHD type deficits are "upstream" from CAPD type deficits. Or, in the current scientific language, ADHD is associated with supramodal impairment, or impairment which is broader than that implicated in CAPD
Sensitivity and Specificity
Dr. Anthony Cacace, associate professor of surgery at Albany Medical College , observes that the challenge here is whether CAPD and ADHD are separate and/or comorbid disorders, part of the same disorder, or mistakes in diagnosis. Dr. Cacace and his colleagues call for greater specificity in the diagnosis of CAPD.
In other words, the criteria cast a broad net, and a variety of students may "meet criteria" for the disorder. CAPD criteria are sensitive because they detect problems. However, Dr. Cacace and others suggest that the current language defining CAPD lacks specificity - the diagnostic language doesn't sufficiently exclude students with problems which are similar to the proposed core impairment in CAPD, but who in fact would be better described by another diagnostic term, or by no diagnosis at all.
ADHD or CAPD?
So, for a neuropsychologist, and for many scientists and clinicians who are taking part in this dialog, the question is something like "doesn't ADHD account for many of the challenges attributed to CAPD?"
Dr. Frank Musiek , professor of audiology and Otolaryngology at the University of Connecticut , might answer "no." In fact, Dr. Musiek and others have suggested that many students have been incorrectly diagnosed with ADHD when they actually demonstrate a set of limitations best described by the term CAPD. He points out that while impairments associated with ADHD affect multiple domains, CAPD deficits are specific to auditory processing.
Now why does this matter? Why should teachers and parents be concerned with the outcome of this academic debate? Treatment decisions depend on diagnostic clarity, and rehabilitation/remediation programs are based on working understandings of students' strengths and weaknesses.
A remediation program based on a working understanding of CAPD, for example, might include auditory training exercises and development of listening and learning strategies. Treatment based on a diagnosis of ADHD might include stimulant therapy and/or training in environmental and contingency management, or development of a broader range of executive and organizational skills. Furthermore, our expectations of students are guided in part by diagnostic terms such as CAPD and ADHD; we adjust our tolerance threshold, and our hopes, by our understanding of what these terms mean.
The Bottom Line
The "true believers" as well as the skeptics both have it partly right. We're still waiting for research to move forward, to clarify the nature of auditory processing dysfunction, and to validate CAPD as a diagnostic label.
A recommended starting point for parents is the pediatrician's office. Discuss your concerns and make sure that medical causes for your child's difficulties have been ruled out. Request referrals for services which your doctor finds appropriate to your situation.
For schools, the Team Meeting is a good starting point. A multidisciplinary discussion will help identify the specific academic concerns. These may overlap with the parents' chief concerns but will be specific to the school situation and to academic achievement.
The school's arsenal for hypothesis testing regarding students with possible auditory processing difficulties includes consultations with a speech and language professional, an audiologist, the school psychologist, or a neuropsychologist.
What's the kid's deal?
Dr. Ross Greene, author of The Explosive Child encourages parents and educators to ask, before planning an intervention, "What's the deal?" This is an informal way of emphasizing the crucial role that accurate and specific diagnosis plays in educational or treatment planning.
For both parents and families, there is no time to wait for the research issues described above to be worked out. Rather than becoming overly wed to one strand of this scientific dialog, and without advocating for one side of the discussion before all the data are in, we might best serve the student by identifying the following:
• Any limitations in general intellectual functioning
• Any specific learning disability
• Any peripheral (as opposed to "central") hearing problems
• Any cognitive limitation which appears to be specific to the processing of spoken language (i.e., CAPD type symptoms); and/or
• A more general limitation with sustained attention, behavioral disinhibition, or distractibility (i.e., ADHD type symptoms).
Then, making use of appropriate and available consultants (such as those mentioned above) to develop remediation plans or environmental manipulation.
In the next article we will continue with the topic of ADHD and CAPD. I've posed some questions directly to CAPD researchers, Drs. Frank Musiek and Anthony Cacace. We'll take a look at their responses. I'll also share a side-by-side review of symptoms which clinical neuropsychologist Dr. David Kent uses in his work with students with ADHD and CAPD.
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References
Barkley, R.A. (1998). ADHD: A handbook for diagnosis and treatment. New York : Guilford Press.
Bellis, T.J. (2002). When the Brain Can't Hear : Unraveling the Mystery of Auditory Processing Disorder. New York : Atria Books.
Cacace, A.T., & McFarland, D.J. (1998). Central auditory processing disorder in school-aged children: a critical review. Journal of Speech Language and Hearing Research. 41(2):355-73.
Cacace, A.T., & McFarland, D.J. (2005). The importance of modality specificity in diagnosing central auditory processing disorder . American Journal of Audiology. 2005 Dec;14(2):112-23.
Carter, L.S. (2000). Scrambled sounds. Dartmouth Medicine , 24:32-37.
Foli, K. (2002). Like Sound Through Water : A Mother's Journey Through Auditory Processing Disorder. New York : Atria Books.
Greene, R. (2001). The Explosive Child : A New Approach for Understanding and Parenting Easily Frustrated, Chronically Inflexible Children. New York : HarperCollins.
Katz, J., Tillery, K.L. (2005). Can central auditory processing tests resist supramodal influences? American Journal of Audiology. 14(2): 124-7; discussion 143-50.
Musiek, F.E., Bellis, T.J., & Chermak, G.D. (2005). Nonmodularity of the central auditory nervous system: implications for (central) auditory processing disorder American Journal of Audiology. 14(2):128-38; discussion 143-50.
Rodriguez, G.P., DiSarno, N.J., & Hardiman, C.J. (1990). Peripheral hearing sensitivity, cognitive function, or linguistic competence. Audiology , 29(2):85-92.
Rodriguez, G.P., DiSarno, N.J., & Hardiman, C.J. (1990). Central auditory processing in normal-hearing elderly adults. Audiology . 29(2):85-92.
Rosen, S. (2005). "A riddle wrapped in a mystery inside an enigma": defining central auditory processing disorder. American Journal of Audiology , 14(2):139-42.